Electroacoustic bone conduction receiver



Jan. 21, 1969 E. M. WEISS ELECTROACOUSTIC BONE GONDUCTION RECEIVER Filed Sept. 13, 1965 INVENTOR BY EQWIN M. WEISS United States Patent 3,423,544 ELECTROACOUSTIC BONE CONDUCTION RECEIVER Erwin M. Weiss, Chicago, Ill., assignor to Beltone Electronics Corporation Filed Sept. 13, 1965, Ser. No. 486,617 US. Cl. 179-107 Int. Cl. H04r 25/00 2 Claim:

ABSTRACT OF THE DISCLOSURE This invention relates generally to improvements in electroacoustic transducers and more particularly to a new and highly advantageous electroacoustic transducer of the bone conduction type, such as are used in hearing aids and the like.

Those skilled in the art of bone conduction transducers appreciate that a serious problem with prior art transducers of this type arises from the transmission of mechanical vibration from the transducer to the case in which it is positioned. This problem is of particular significance in hearing aids assemblies wherein the bone conduction receiver and the microphone are positioned in closely spaced relationship within a rigid casing. Such circumstances give rise to vibration feedback from the receiver to the microphone which can result in highly unsatisfactory performance of the hearing air.

The electroacoustic transducer invention disclosed in my prior Patent No. 3,019,304, issued Jan. 30, 1962, serves to minimize this feedback problem, in addition to several other problems which also affect the performance of a hearing aid. It is a general object of this invention to provide a further improvement over the prior art bone conduction transducers, which improvement serves to materially reduce the amount of vibrational energy transferred from the transducer to the case during the operation of the transducer.

It is another object of this invention to provide a new and improved bone conduction transducer which is characterized by a substantial reduction in the weight and number of its component parts, to thereby facilitate its use in relatively compact apparatus, such as head worn hearing aids and the like.

It is a still further object of this invention to provide such an improved bone conduction receiver, as described, which utilizes pre-loaded torsion suspension of the receiver within the hearing aid case to make the fitting of the hearing aid less critical and wherein the receiver can be pre-loaded into the case in a relatively simple manner.

The novel features which are characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following description taken in conjunction with the accompanying drawings in which:

FIGURE 1 illustrates a temple member of an eyeglass type hearing aid in which the bone conduction receiver of the present invention may be embodied;

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FIGURE 2 is a plan view of an illustrative embodiment of bone conduction receiver construction in accordance with the invention; and

FIGURE 3 is a cross'sectional view of the illustrative bone conduction receiver taken substantially as shown on line 33 of FIGURE 2.

Referring now to the drawing, and more particularly to FIGURE 1 thereof, there is shown one type of hearing aid eyeglass temple member with which the invention may be used. It will be appreciated by those skilled in the art that the novel principles of the present invention are not limited for use in an eyeglass type of hearing aid but find a wide variety of other uses which can take advantage of its features.

The illustrative eyeglass temple member 10 shown in FIGURE 1 generally is of the type which comprises a case having a hollow interior capable of receiving all of the component parts of a complete hearing aid. These parts may include the normal and well known components of an operable hearing aid such as a microphone for picking up sound, an amplifier for amplifying the sound, a power source such as a battery, and a receiver for communicating the amplified sound energy to the wearer. In the illustrative eyeglass temple member shown in FIG- URE 1, the receiver takes the form of a bone conduction transducer which embodies the present invention. The receiver 16 is located at the rear portion 12 of the temple member 10 remote from the hinge member 14 provided for hinged connection to the front lens frame of the eyeglasses. The bone conduction receiver 16 is positioned at the rear portion 12 of the temple member so that when the eyeglasses are worn by the wearer, the bone conduction receiver will be in vibrational energy transmitting contact with the mastoid area of the wearers head.

Reference is now made to FIGURES 2 and 3 of the drawing for a detailed description of the construction and operation of the bone conduction receiver 16 embodying the present invention. Positioned within the case 18 of the hearing aid temple member 10 is a rigid platform member 20. Advantageously, the platform member 20 is pivotally mounted at one end to the case 18 to permit its free end to be vibrated relative to the case in accordance with the sound energy picked up and amplified by the hearing aid. Since the remainder of the hearing aid components are conventional and wellknown, they will not be further described herein, and the present description will be limited to the novel details and operation of the bone conduction receiver 16.

A conventional bone conduction vibrator 22 is attached to the under surface of the platform member 20. The bone conduction vibrator 22 may include any suitable electromagnetic assembly which will cause the platform member 20 to vibrate in accordance with the electrical energization of the vibrator by the hearing aid amplifier.

Preferably, an elongated slot 24 is provided within the platform member 20 for enabling the position of the vibrator 22 to be selectively adjusted on the platform 20. If desired, the elongated slot 24 may take the form shown in FIGURES 2 and 3 wherein the slot comprises a lower portion 26 of a relatively narrow width and an upper portion 28 of a relatively wider width. With such a construction, the vibrator 22 may be mounted on the platform 20 by means of a screw fastener 30 having a head of greater diameter than the width of the lower portion 26 of slot 24. In this manner, the vibrator 22 is supported on the platform 20 by the head of the screw fastener 30 which rests upon the cooperating flange defined by the slot portions 26 and 28. This arrangement permits the position of the vibrator 22 to be adjusted longitudinally on platform 20 so as to enable the frequency response of the system to be adjusted and to adjust the amount of feedback for different hearing aid cases and dimensions. When the proper position of the vibrator 22 on the platform is determined during assembly of the receiver, the screw fastener 30 may be tightened to securely hold the vibrator 22 in place. If desired, suitable adhesive may be =used to fix the bone vibrator in its proper position.

In accordance with a novel of the present invention, the bone conduction receiver assembly is mounted in case 18 in a manner which enhances the mechanical isolation between the receiver and the case, and in which facilitate the assembly of the apparatus and makes the fitting of the hearing aid less critical.

As shown in FIGURES 2 and 3 of the drawing, the case 18 is fully open at the portion which normally rests against the wearers head. This opening permits the bone conduction receiver 16 to be easily positioned within the case 18 and to be mounted by pre-loaded torsion suspension therein so as to eliminate any need for frame adjustment of the eyeglasses when it is fitted to the wearers head. The platform 20 is mounted to the case 18 by means of a pair of depending legs 32, positioned on opposite sides of the platform. A pair of pre-stressed visco-elastic torsion isolators 34 are respectively positioned between the legs 22 and the inner walls of case 18.

The isolator elements 34 advantageously may be formed of rubber or any other suitable viscoelastic material. The platform 20 may be torsionally pre-loaded in the case 18 by inserting the platform at a desired acute angle relative to the case 18 and securing the platform legs 32 to the isolator elements 34. Thus, when the platform 20 is depressed so as to be torsionally pivoted on the isolator elements 34, the resiliency of the latter will pre-load the platform 20 within the case 18 so that the free end of the platform will be urged toward the head of the wearer. In one illustrative embodiment of the present invention, it was found advantageous to insert the platform 20 into the case 18 at an angle of 90 degrees relative to the case such that when the free end of the platform 20 was pivoted downwardly into the case, a desirable amount of torsion pre-loading was maintained.

As stated above, the electrical energization of the vibrator 22 by the hearing aid amplifier causes the platform 20 to be vibrated in a manner corresponding to the sound energy to be transmitted to the wearer. The transmission of this vibratory energy is enhanced and made more effective by the use of flexible contact button 36 maintained on the side of the platform 20 opposite from the vibrator 22. As pointed out in my prior Patent No. 3,019,304 the flexible contact button 36 may comprise a pouch of resilient material filled with a plurality of small particles, such as glass beads or the like. Due to its resilient characteristics, the button 35 will conform to the contour of the wearers mastoid area to provide uniform contact pressure against the head and thereby increase wearer comfort as well as uniformity of bone conduction receiver response. Further, as shown in FIGURE 3 of the drawing, the entire receiver assembly within the case 18 may be protected from dust or other damaging substances by means of a flexible dust cover 38 positioned over the case opening.

It now can be understood by those skilled in the art that the present invention serves to improve vibration isolation between a bone conduction receiver and the case, while at the same time, permitting the complexity and whight of the receiver to be materially reduced. The invention has the further advantage of low-torsion stiffness, and the static force of the receiver against the head changes very little between the operating positions of the platform member.

While there has been shown and described a specific embodiment of the present invention, it will, of course, be understood that various modifications and alternative constructions may be made without departing from the true spirit and scope of the invention. Therefore, it is intended by the appended claims to, cover all such modifications and alternative constructions as fall within their true spirit and scope.

What is claimed as the invention is:

1. The improvement of an electroacoustic transducer assembly having improved vibratory isolation characteristics comprising a rigid case having an opening for receiving an electroacoustic transducer, said transducer including an elongated platform member formed of relatively rigid material, means for pivotally mounting one end of said platform member to the rigid case, said means comprising pre-stressed torsion isolator elements positioned between opposite sides of said platform member and said case to minimize vibratory feedback from the platform to the case during the operation of the electroacoustic transducer, an electromagnetic vibrator secured to one face of the platform member at a point spaced from its pivoted end for causing the platform member to vibrate about its pivoted end in a manner corresponding to the energization of said electromagnetic vibrator, means for adjusting the spacing of said vibrator relative to the pivoted end of the platform for adjusting the frequency response and feedback of the assembly, and a resilient contact button secured to the face of the platform member opposite the vibrator for transmitting the vibrations of the platform member to the skin of the wearer.

2. The improvement of an electroacoustic transducer assembly having improved vibratory isolation characteristics comprising a rigid case having an opening for receiving an electroacoustic transducer, said transducer including an elongated platform member formed of relatively rigid material, means for pivotally mounting .one end of said platform member to the rigid case, said means comprising pre-stressed torsion isolator elements positoined between opposite sides of said platform member and said case to minimize vibratory feedback from the platform to the case during the operation of the electroacoustic transducer, an electromagnetic vibrator secured to one face of the platform member at a point spaced from its pivoted end for causing the platform member to vibrate about its pivoted end in a manner corresponding to the energization of said electromagnetic vibrator, means for adjusting the spacing of said vibrator relative to the pivoted end of the platform for adjusting the frequency response and feedback of the system, said means comprising an elongated slot formed in said platform member, and fastened means longitudinally slidable in said slot and secured to said vibrator, and a resilient contact button secured to the face of the platform member opposite the vibrator for transmitting the vibrations of the platform member to the skin of the wearer.

References Cited UNITED STATES PATENTS 3,019,304 1/1962 Weiss 179114 Re. 22,658 8/1945 Koch 179-107 2,264,684 12/1941 Weidenman 179107 KATHLEEN H. CLAFFY, Primary Examiner A. MCGILL, Assistant Examiner.

US. Cl. X.R. 

